They eat all day not just in the mornings.
That’s not necessarily the case. Seed eaters with crops can gorge themselves with food which will last quite a while, birds without crops need regular food.
Consequently a pigeon can easily survive a couple of days without food, a crow however probably wouldn’t – they would quickly become too weak to fly and find food.
Also fat reserves play a part – pigeons will have some but crows have no significant amounts of fat.
Edit: And the comments with regards to birds and their routines are very valid imo.